1. Field of the Invention
The present invention relates to a recording medium supporting member, a recording medium conveying device for use in an image forming apparatus and an image forming system, and a method of forming an image on a recording medium.
2. Discussion of the Background
It is know to use image forming apparatuses that form images on both sides of a recording medium, such as a transfer sheet, by a switchback two-side transfer method.
In the switchback two-side transfer method, a visual image, such as a toner image that has been formed on an image bearing member, is transferred onto one side of a recording medium by a transfer device, and is then fixed onto the one side of the recording medium by a fixing device. The recording medium is then reversed by a reversing path, etc., and is conveyed again to the transfer device and the fixing device so that another visual image that has been formed on the image bearing member is transferred and fixed onto the other side of the recording medium.
In the above image forming apparatuses using the switchback two-side transfer method, because a switchback mechanism for reversing a recording medium to be conveyed again to the transfer device and the fixing device is necessary, the cost of the image forming apparatus may be increased. Further, it may be difficult to perform a high speed image forming operation on each side of a recording medium. Moreover, a sheet jam may tend to occur during the switchback process because a recording medium may curl when an image is fixed onto one side of the recording medium by heat.
Japanese Patent Laid-open Publications Nos. 1-209470 and 10-142869 each describe an image forming apparatus employing a one path two-side transfer method in which visual images are transferred onto both sides of a recording medium in a two-side transfer device. The recording medium is then conveyed to a fixing device, where the visual images are fixed onto both sides of the recording medium at the same time.
In the above-described image forming apparatus, because the above-described switchback mechanism and process are not necessary, the increase in cost of the apparatus and occurrence of sheet jam caused by the use of the switchback process may be avoided. Further, a high speed image formation on both sides of a recording medium may be performed.
Generally, an image forming apparatus employs a fixing device that fixes a visual image, such as a toner image, onto a recording medium, such as a transfer sheet, while heating the visual image. If such a fixing device is provided relatively close to a two-side transfer device, a visual image may be fused under the influence of heat generated from the fixing device, thereby causing image deterioration. Conversely, if such a fixing device is provided relatively apart from a two-side transfer device, it may be difficult to convey a recording medium from the two-side transfer device to the fixing device.
In order to address the above-described problems, a background image forming apparatus includes a fixing device and a two-side transfer device provided apart from each other at some distance, and a spur between the fixing device and the two-side transfer device so as to guide conveyance of a recording medium having unfixed visual images. In such a background image forming apparatus, the above-described image deterioration due to heat generated from a fixing device is prevented, and a recording medium is effectively conveyed from a two-side transfer device to a fixing device.
However, in the above-described background image forming apparatus, an unfixed visual image on a rear surface of a recording medium (i.e., a surface of a recording medium facing the spur) may be disturbed before being fixed by the fixing device due to sliding contact with the spur. Further, when an image forming substance such as a toner of an unfixed visual image is transferred to the spur from a rear surface of a recording medium due to sliding contact with the spur, the image forming substance may adhere to a succeeding recording medium, thereby adversely affecting a rear surface of the succeeding recording medium.